This invention relates to locking devices, and more particularly to an improved electronic locking device that is operated by a novel, light-transmissive key. Even more specifically this invention relates to an electronic locking device having light-sensitive elements connected by light pipes with openings on a keyway in the device, and which are controlled by a key having a light transmissive shank coded to transmit light to predetermined spots in the keyway.
There are a number of known locking devices, the operations of which embody a combination of optical and electronic technology. Frequently these devices are controlled by a key, which embodies a code that is read out, or sensed, when the key is inserted into an appropriate keyway device. Typically, however, the shanks of such keys must be carefully machined or shaped to form thereon the usual notches and teeth which are designed to operate the associated tumblers or special circuit operating elements. In other cases prior electronic locking devices have required rather complicated or expensive circuitry to perform the desired locking function.
U.S. Pat. No. 4,090,175, for example, teaches an opto-electronic locking device operated by a perfectly flat, plane key having intermediate its ends a plurality of spaced holes or apertures, and having formed on its inner end a plurality of spaced projections, which are adapted mechanically to operate plungers when the key is inserted into a slit or keyway in the associated key cylinder. A plurality of spaced light pipes are located at one side of the cylinder to direct beams of light onto one side of the key shank. Only when the openings in the shank are properly aligned with these beams will they pass through the shank and onto spaced, light-responsive elements located at the opposite side of the cylinder, thereby completing a circuit necessary for operation of the locking device.
The obvious disadvantage of this type of device is that there are only so many locations on the shank of the key through which openings can be made in order to provide an optical code different for each different locking device. Moreover, each key shank must be drilled or otherwise provided with a plurality of openings which are located (at least with respect to one opening) differently from those openings made in the shank of other keys.
U.S. Pat. No. 3,733,862 also discloses a combined mechanical and photoelectric lock; but again, identifying data or coding circuits are energized by virtue of light which is directed transversely through openings in the flat shank of an otherwise conventionally shaped key. Likewise, U.S. Pat. No. 3,639,906 utilizes combination opto-electronic device, but again the operating key is of conventional configuration.
U.S. Pat. No. 3,786,471 and No. 3,029,345 also disclose electronic locking systems, but each uses perfectly flat keys which are perforated or notched along their edges to provide the necessary coding.
U.S. Pat. Nos. 3,500,326; 3,599,454; and 3,889,501 also disclose, in essence, generally conventionally shaped keys for operating electronic locking devices.